The overall objective of the proposed research is to characterize an antigen(s) present in the capsule of Clostridium perfringens which may serve as the basis for the preparation of a monovalent immunospecific reagent for the detection, identification and enumeration of the species. Past attempts to develop a universal and specific serological reagent for C. perfringens have not been successful because more than 100 distinct serotype strains of C. perfringens indicates the possibility of employing a minor cell envelope component, whch is not normally immunogenic, as the basis for the development of an immunospecific reagent. Initial biochemical studies will seek to establish that a "common antigen(s)" exists for the C. perfringens species; the polysaccharide antigen(s) will be isolated in a purified state from cells of selected serotype strains, and the relationship of the chemical composition of the antigen(s) to its immunological properties will be studied. An immunogenic preparation of the "common antigen(s)", obtained by coupling the polysaccharide to protein or by the formation of a protein-polysaccharide complex, will be used to obtain specific antiserum. The antiserum or its fluorescent antibody derivative will be used to determine the distribution of the "common antigen(s)" within the species by performing a comprehensive evaluation on all available strains. In addition the reagents will be tested against other bacterial species, in particular species, in particular other members of the genus Clostridium, and strains of those species most likely to be confused with C. perfringens. A procedure will be developed for the rapid detection and enumeration of C. perfringens in cultures, clinical specimens, foods, and environmental samples. The usefulness of the reagent as an aid to clinical investigations of diseases involving C. perfringens will be evaluated.